Hello Kitty: Roller Rescue Cheats - GameCube

Unlock Character Profiles
After rescuing a character, their profile is unlocked. However, you must also pay differing values of money to view each character profile after they are unlocked. Profiles can not be viewed until Mimmy is rescued. To unlock Margaret White, she must be rescued twice.

Anthony White - Unlock Mimmy
Badtz-Maru - Stage 14: Collect all 3 of the keys. After obtaining the blue key, go 2 rooms back and unlock the doors on your right.
Block Kitty - Complete Stage 14.
Daniel - Stage 13: After opening 2 doorways, go to the left of room 3 and smash all the boxes to find Daniel behind them.
George White - Unlock Mimmy.
Hello Kitty - Unlock Mimmy.
Keroppi - Stage 2: After going over the bridge, jump over the steel blocks onto the roof. Follow 2 planks along the roofs to find Keroppi.
Kiki - Stage 5: After smashing the 2nd lot of barrels, go through the newly opened door on your right and to the far right of the train track to rescue Kiki.
Koroppi - Unlock Mimmy.
Kurin - Stage 10: In the large parking area, destroy the blue block before it runs through the hole in the fence to get Kurin from it.
Lala - Stage 4: Find the yellow key from a blue block through the pink door, and open the yellow door near you to find Lala.
Margaret White (1) - Stage 1: After going through the pink door, smash all the boxes to find Margaret White behind them.
Margaret White (2) - Stage 11: After finding My Melody, make your way to the center ledge on the left wall to rescue Margaret White.
Mary White - Unlock Mimmy.
Mimmy - Stage 4: After opening the pink door, go to the right, jump over the hedge, and pull the lever. Go back to the cup ride and defeat all enemies.
Monkichi - Stage 7: At the freezer entrance turn right and smash all the boxes to the right to get to Monkichi.
My Melody - Stage 11: After running from the giant ball, turn to the right and talk to My Melody.
Pochacco - Stage 8: Make your way to the far right corner of the room and jump to the top of a ledge here to find Pochacco.
Pochi - Stage 13: After pressing the button to turn the bridge around, go across and talk to Croc to the left of you.
Purin - Stage 4: After opening the yellow door, go to the far right. Pull the lever when the "Help!" is positioned at the bottom of the ferris wheel.
Runabouts - Stage 10: After defeating the big block, go through the new opening and straight forward until you find Runabouts.

Unlock Movies
After unlocking each, you must also pay the $200 for each cinematic to view them:

"The Unexpected Victory" clip - Complete the game as Badtz Maru.
"So Long! Round Earth!" clip - Cinematic Lose against the final countdown boss.
"The Taste of Victory" clip - Cinematic Win against the final countdown boss.

Unlock Costumes
Cheerleader Costume A Defeat all the cheerleader blocks in Messy Park (Level 5).
Cheerleader Costume B After unlocking Cheerleader Costume A, play Messy Park again (defeating all the cheerleaders).
Badtz-Maru - Play through the game and complete it with the good ending and Badtz-Maru's profile unlocked. Wait for the credits to roll, then choose to start a new game. You will have a character choice of either Hello Kitty or Badtz-Maru.

Unlock Weapons
Magical Wand - Default weapon from the start
Mambo - Complete four levels using a partner
Toy Hammer - Rescue four partners

Happy Birthday Hello Kitty
Play the game any time during the month of November (according to your GameCube's clock) and the title screen and loading screens will now be Birthday-themed to celebrate Hello Kitty's birthday on November 1st.